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Chapter 8 |
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As any farmer will tell you, no two farms are alike. Each has its unique configuration of soil type and slope, crop or livestock production, farm buildings, equipment, and people. Programs to preserve and enhance the farm environment must therefore be tailored to the specific needs of a given operation and the people who run it. This chapter describes a number of regulatory initiatives that encourage soil conservation. Most of them share an emphasis on farmer-centered planning, because experience has shown that farmer cooperation, often based on site-specific initiatives, is central to the success of soil conservation programs.
Since the dust bowl years of the 1930s, when soil erosion and drought were at their worst levels in decades, governments around the world recognized that farmer education is key to land stewardship. In the intervening 70 years, many governments developed ambitious agricultural "extension" programs to provide conservation information to farmers. These programs are usually staffed by agricultural professionals—people who understand the technological and economic issues facing farmers and can discuss options for a particular farm operation. However, securing farmer cooperation for these programs is much more difficult than it might appear. Farmers are understandably nervous about any action that might adversely affect farm income. Those whose families have worked a farm for generations may be skeptical that governments have much to teach them about the land they know so well. Surveys show that farmers prefer to get their information from other farmers. In fact, farmers rank other farmers first, government experts next, and university researchers last in terms of the value of their information—and the trust to be placed in it. As a result, over the past decade, farming organizations have begun to assume more of the responsibility for community outreach at a grassroots level.
This approach has proved a powerful one. In Canada, Ontario's highly successful Environmental Farm Plan (EFP) program, for example, was started by Ontario farming organizations and has involved farmers at every stage of development. It involves voluntary preparation of documents that highlight a farm's environmental strengths and weaknesses and propose a realistic action plan to correct identified problems. More than 20% of Ontario farmers now participate in the EFP process. The power of this farmer-to-farmer outreach can perhaps be traced to the strong sense of heritage most farm families feel. Learning from other farmers how to protect and improve their land is one way farmers can protect that heritage for their family's future.
Case Study: Estimating Soil Loss
Farmer-to-farmer education programs are critical in encouraging sound land stewardship practices. But how does the farming community know what works and what does not?
On-farm experience is, of course, a persuasive teacher. When a new practice has been tried, its success or failure is very quickly known within the farming community. But such an approach is necessarily reactive and requires that a farmer risk capital costs and future yields without knowing the impact of the techniques being tried. Recognizing this problem, U.S. Department of Agriculture researchers working in the 1950s and 1960s developed a simple predictive equation based on observations of dozens of farm fields over many years. This equation, the Universal Soil Loss Equation (USLE), is now the single most widely used predictor of soil loss potential in the world.
Essentially, the USLE allows farmers to estimate rainfall-induced soil erosion under different land management strategies. For instance, if a farmer is having trouble with gully erosion on a portion of his land, he can use the USLE to see what management approaches might help him solve the problem.
The USLE is a simple equation that predicts field soil loss in tons per acre based on six factors:
A=R*K*LS*C*P
R= the rainfall and runoff erosivity index
K= the soil-erodibility factor
L= the length of slope factor
S= the degree of slope factor
C= the cropping-management factor
P= the conservation practice factor.
These factors are multiplied together to generate an estimate of potential soil loss, A= erosion loss, Mg/ha/yr or ton/A/yr.
What is meant by "factor"? In the USLE, the term factor refers to a numerical value assigned to a particular field characteristic (e.g., soil erodibility) based on many years of observation. These values are available in published tables or diagrams (nomograms) for easy reference by users of the USLE. The values currently available are based on more than 10,000 plot-years of observation at dozens of agricultural sites around the United States. (A plot-year is one year of observation of a single plot of land.)
The vast quantity of data now available for the USLE represents a huge range of operating conditions and probably includes most conditions that would be found outside the United States. Its value lies in its ability to predict relative impacts—in other words, to say that a particular activity will result in more, or less, soil erosion than another activity.
The particular value of the USLE lies in its simple form and easily understood inputs. It is a tool that is readily available in literature, on the Web, and one that is widely used in the agricultural management community. It forms the basis for the many computer simulation models of drainage and erosion that inform public policy on soil conservation and land stewardship. In a sense, the USLE has become part of the universal language of soil conservation—a powerful basis for communicating across cultures, disciplines, and agricultural environments.
Click on Soil and Water Conservation Society to access the site for one of North America's premier soil conservation associations. Information about international soil erosion concerns can be found at the Website for the International Erosion Control Association. Click on Agriculture Canada to see Canadian soil conservation information. Typical agricultural extension sites can be accessed by clicking on Cornell Extension and Florida Cooperative Extension.
Information about the Universal Soil Loss Equation and its application in the prediction of soil erosion can be found by clicking on USLE. An updated version of the USLE, the Revised Universal Soil Loss Equation, can be found by clicking on RUSLE. The State of Pennsylvania makes reference to the Revised Universal Soil Loss equation in its Erosion and Sedimentation Control Manual for Farmers.
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